Shrubs of Wisconsin

Vaccinium cespitosum Michx.
dwarf bilberry
Family: Ericaceae
plants in habitat plant plant leaves winter buds flowers

Vaccinium cespitosum is a small and inconspicuous shrub, easily overlooked. Plants spread vegetatively, and each roughly vertical aerial stem is usually less than 30 cm tall--many plants in my experience being less than 20 cm tall in Wisconsin. Leaves are alternate and simple, finely toothed and usually less than 1 cm (rarely to 2) wide and about 2 to 2.5 times as long. The blades are obovate and often long-tapered to the base. Buds have only 2 visible outer scales. Flowers are attached singly in the leaf axils and develop a blue berry. The small size, finely toothed leaves and 2 bud scales will distinguish this species from our other Vaccinium shrubs.

This species is endangered in Wisconsin and in addition to being rare it is easy to overlook. The plants often grow with our common blueberry (Vaccinium angustifolium), but V. cespitosum is even smaller. It is the only host species for the Wisconsin endangered Northern Blue butterfly.

If it is growing with Vaccinium angustifolium, the two species can be distinguished by flowers, those of V. cespitosum attached 1 or 2 in the axils of leaves and V. angustifolium flowers in racemes or dense clusters of 3 or usually more. However if the plants do not have flowers or fruits, V. cespitosum winter buds have only two visible outer bud scales (see above) and V. angustifolium has more scales--often 4-6 can be easily seen. Also V. cespitosum leaves tend to be oblanceolate and often long-tapering to the base and V. angustifolium leaves are usually elliptic. Any single leaf may not be very satisfying in this regard, but usually looking at a selection of multiple leaves will work based on leaf shape.


known Wisconsin distribution


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